The present invention relates to a power controller for an engine controller for an engine system having an internal combustion engine and an electric generator coupled to the internal combustion engine. The present invention also relates to a corresponding engine controller and to a corresponding engine system.
In automotive engineering, an attempt is made to reduce the fuel consumption of modern motor vehicles further and further. In addition to improvements to conventional internal combustion engines, electric motors are also being used more and more often in vehicles. In this case, the electric motors can support the internal combustion engine, for example. This principle is used in so-called hybrid vehicles.
Alternatively, however, the electric motor can also replace the internal combustion engine in the vehicle. A vehicle in which the electric motor is the only drive motor is also called an electric vehicle. On account of the limited capacity of currently available electric energy stores, the range of such electric vehicles is limited.
A so-called range extender provides one possible way of increasing the range of electric vehicles. In electric vehicles with a range extender, in addition to the purely electric drive system, an independent internal combustion engine is coupled to an electric machine in order to produce electric energy for the drive. Depending on the driving state and state of charge of the battery, the electric machine is intended to produce a desired electric power.
A possible range extender is shown in US 2013 300 126 A1, for example.
The power produced by the range extender is usually set by selecting the torque and speed of the internal combustion engine. In order to set the torque in a gasoline engine, the throttle valve and the ignition angle adjustment device are used as the actuator. The adjustable injection duration and the injection angle are used to set the torque in a diesel engine.
However, the best efficiency for the instantaneous speed is established only with a particular torque in internal combustion engines. Since the speed has to be regulated by changing the burner torque, power regulation at optimum efficiency is not possible with this structure.
In order to be able to carry out power regulation at optimum efficiency, the burner torque must not be the output of the speed regulator, but rather must be freely selectable. The speed must be regulated using the torque of the electric machine. This structure is illustrated in FIG. 12.
FIG. 12 shows the structure of a control or regulating system for an engine system, having a superordinate control device 100 which requires a desired electric power 102 from the internal combustion engine control device 103, inter alia from the state of charge 101 of the vehicle battery, also called SOC. In this case, the engine speed can be limited to a maximum value 104 on the basis of specifications with regard to the generation of sound.
In the range extender system—illustrated by way of example here in the internal combustion engine control device 103—a power regulating function 105 regulates the electric output power to the predefined desired power 102. The power regulating function 105 calculates the torque 106 to be output by the internal combustion engine 120 and the speed 107 which is to be set at the generator 121 and is required by an electric machine control device 108. The internal combustion engine control device 103 also contains a function 109 which substantially sets the torque 106 in the internal combustion engine 120 by regulating or controlling the suitable actuators, such as the throttle valve position, the ignition angle and injection quantities and times, depending on the type of internal combustion engine 120.
In the electric machine control device 108, a speed regulating function 110 ensures that the desired speed 107 is adjusted. This can be carried out, for example, using a PI regulator, the input of which may be the measured actual speed and the output of which may be the torque at the electric machine 121. The instantaneous electric machine current 111 and the high voltage 112 are transmitted to the power regulating function 105 which is illustrated here by way of example in the internal combustion engine control device 103. The battery management system 113 continuously determines the SOC 101 and the charging limits of the high-voltage battery 114.